How to save descriptive flexfield columns in the manage items page?

We are experiencing an issue on the "manage items" page in the Prodcut information managemen;, we are not able to add individual descriptove flexfields as filters; we can only add the DFFs as a group when selecting the columns to display.

Also, once we add the DFF columns and leave the page, the selection is not saved. When we open the page again, we have to add the DFF columns every time.

Could you please check if this is the expected behavior or if there is a way to keep the selected DFF columns saved?

Thank you, Best.